Fateful
Part of speech: adjective
Definition: Momentous, significant, setting or sealing ones fate. Determined in advance by fate, fated.
Decisive
Part of speech: adjective
Definition: Having the power or quality of deciding a question or controversy; putting an end to contest or controversy; final; conclusive.Marked by promptness and decision.
Example sentence: When you really start figuring things out as a quarterback, you realize you don't have to be perfect every time, but you do have to be quick and decisive.